Driver support or assistance systems for supporting and unburdening the operators of motor vehicles have been in testing for several years and partially already on the market. In this context, especially spacing distance controlled speed regulation systems, so-called ACC systems (Adaptive Cruise Control) are to be mentioned, with which target objects are automatically detected in higher speed ranges of the motor vehicle (approx. 40 km/h to 160 km/h), and target objects that are classified as relevant for one's own driving are reacted to comfortably, that is to say with limited acceleration or deceleration values, by adaptation of one's own driving speed. Additionally, the operator of the motor vehicle can be informed regarding the “danger potential” of target objects by (for example optical or acoustical) warning devices, and can be warned of potential collisions with rapidly approaching obstacles. The driver assistance systems are generally switched on and off manually by the operator of the motor vehicle, and can be overridden and/or deactivated by the driver.
It is desirable to expand the speed range of the motor vehicle for the speed regulation system toward lower vehicle speeds, and especially also to carry out a regulation of the speed of one's own motor vehicle all the way to a standstill; hereby, for example, a “stop and go” function can be realized, by means of which, upon approaching a traffic jam, it is possible to automatically close ranks up to the already-stopped last vehicle or to stop before other obstacles. However, the acceptance of a larger speed range for the speed regulation, and the desire to have a speed adaptation that is automatic to the extent possible in the approaching phase to resting (very slow or standing) target objects, requires a high deceleration capacity of the speed regulation system and also the inclusion of stationary target objects (especially standing obstacles) into the regulation concept.
In known driver assistance systems, two different operating modes are defined: in the EP 0,590,588 B1, a normal driving mode is provided for the “normal” speed range and an overload driving mode is provided for low vehicle speeds (for example stop and go); in the spacing distance warning system of the DE 32 22 263 A1, a switch-over between two operating modes (selective monitoring for the complex traffic, typical conventional spacing distance monitoring for the “normal” traffic) is carried out automatically or manually. In this regard it is disadvantageous that the transitions between the two operating modes are complicated, that the constant differentiation between the two operating modes overburdens the operator of the motor vehicle (especially the operator often does not know in which operating mode he is situated at the moment), and that erroneous reactions of the system in the form of an unsubstantiated braking reaction result in decelerations that are often abrupt for the operator of the motor vehicle (it must be made possible for the motor vehicle to stop automatically before a stationary or standing obstacle), whereby the acceptance of such a driver assistance system by the operator of the motor vehicle is greatly impaired.